gadt corner

g.ml

module Propagation = struct
  type _ t =
      IntLit : int -> int t
    | BoolLit : bool -> bool t

  let check : type s. s t -> s = function
    | IntLit n -> n
    | BoolLit b -> b

  let check : type s. s t -> s = fun x ->
    let r = match x with
    | IntLit n -> (n : s )
    | BoolLit b -> b
    in r
end